Buffer sizing and Video QoE Measurements at Netflix.

In this paper we report on measurement of Netflix video traffic, to understand how the size of router buffers affects the quality of video seen by the end-user (i.e. video QoE). In certain locations, Netflix streams video over TCP New Reno from racks of servers that are directly connected to large routers, which in turn directly peer with commercial ISPs. We vary the size of the router buffers during periods of persistent congestion, and log metrics such as the number of rebuffering events, video quality, and video play delay. We observe buffers that are too small and too large, both of which worsen video QoE. Our results are for a specific, but we believe interesting, case: a router carrying large numbers of long-lived TCP flows, shedding light on how buffers should be sized by CDNs and video content providers. We find that the generality of our results is limited by the specific internal workings of the VOQ-based chassis routers used in our experiments, which have a different buffer architecture than prior work. We conclude that the routers complicate-and potentially mask-our clear understanding of buffer sizing.